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Signal generator, radar device

a signal generator and radar technology, applied in the direction of oscillator generators, instruments, measurement devices, etc., can solve problems such as difficulty in suppressing phase nois

Inactive Publication Date: 2015-06-16
KK TOSHIBA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The patent describes a circuit that generates signals based on an input control signal. The circuit includes an oscillator that produces an oscillation signal, a digital phase detector that measures the phase of the signal, a differentiator that calculates the frequency of the signal, a comparator that compares the desired frequency with the measured frequency, and a low-pass filter that removes high-frequency components. The circuit also includes a digital-to-analog converter that converts the high-frequency error information into an analog control signal. The technical effect of this circuit is to provide a more accurate and reliable control signal for generating signals in a variety of applications.

Problems solved by technology

However, there are problems in the conventional methods in which it is difficult to suppress a phase noise of the voltage controlled oscillator and to maintain a linearity of the FMCW signal, and a means to correct the error is additionally required.

Method used

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first embodiment

(Operations of First Embodiment)

[0038]Subsequently, operations of the signal generating circuit 1 according to the first embodiment are described with reference to FIG. 3. FIG. 3 illustrates a transfer function of the signal generating circuit 1 illustrated in FIG. 1. In FIG. 3, a symbol φFMCW is a phase noise of the FMCW signal, a symbol “φR” is a phase noise of the reference signal Ref, a symbol “φnR” is a phase noise of the reference signal, a symbol “N” is a frequency division number of the frequency divider 10, a symbol “φnTDC” is a quantization noise generated at the digital phase detector 15, a symbol “HLPF” is a transfer function of the LPF35, a symbol “Dgain” is a product of a gain of the variable gainer 40 and a gain of the multiplier 45, a symbol “KDAC” is a gain of the current output DAC50, a symbol “φnDAC” is a quantization noise generated at the current output DAC50, a symbol “Ks” is a gain of the integrator 55, a symbol “fref” is a frequency of the reference signal, a...

second embodiment

(Second Embodiment)

[0046]Next, a signal generating circuit according to a second embodiment is described in detail with reference to FIGS. 4, 5A to 5D. As illustrated in FIG. 4, a signal generating circuit 2 of the second embodiment is the one in which a control loop of a gain calibration is added to the signal generating circuit 1 of the first embodiment. In the following description, common reference numerals are used to designate elements common to the signal generating circuit of the first embodiment, and redundant descriptions are not given.

[0047]As illustrated in FIG. 4, the signal generating circuit 2 of the second embodiment includes a differentiator 60 performing a differential process of the frequency setting code output by the code generator 25, and a gain calculator 65 calculating a ratio between the differentiation result and the digital error information input to the current output DAC50 and providing the calculation result for the multiplier 45, in addition to the sig...

third embodiment

(Third Embodiment)

[0059]Next, a signal generating circuit according to a third embodiment is described with reference to FIG. 8. As illustrated in FIG. 8, a signal generating circuit 3 of this embodiment is the one in which the control loop of the gain calibration in the signal generating circuit 2 of the second embodiment is changed. In the following description, common reference numerals are used to designate elements common to the signal generating circuits of the first and second embodiments, and redundant descriptions are not given.

[0060]As illustrated in FIG. 8, the signal generating circuit 3 of the third embodiment includes an integrator 70 and an adder 75 in addition to the elements of the signal generating circuit 1 illustrated in FIG. 1. Besides, the signal generating circuit 3 of this embodiment includes a code generator 26 instead of the code generator 25.

[0061]The code generator 26 in the signal generating circuit 3 of this embodiment outputs a fixed value of the frequ...

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Abstract

A signal generating circuit includes an oscillator to produce an oscillation signal controlled in oscillating frequency by an analog control signal. The circuit includes: a digital phase detector detecting phase information of the oscillation signal and outputting digital phase information; a first differentiator differentiating the digital phase information and outputting digital frequency information; a comparator comparing a frequency setting code setting the oscillating frequency with the digital frequency information and outputting digital frequency error information; and a low-pass filter removing a high-frequency component of the digital frequency error information. The circuit further includes: a D / A converter converting the digital frequency error information of which high-frequency component is removed into analog frequency error information; and an integrator integrating the analog frequency error information, to convert into analog phase error information, and outputting the analog phase error information as the analog control signal.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2011-134255, filed on Jun. 16, 2011; the entire contents of which are incorporated herein by reference.FIELD[0002]Embodiments described herein relate generally to a signal generating circuit, and a radar device.BACKGROUND[0003]A radar device using an FMCW (Frequency Modulated Continuous Wave) signal receives the FMCW signal transmitted from a transmitter and reflected by an object, and multiplies the received signal and a transmitted signal transmitted at the receiving time. Here, an output signal frequency of a multiplier is determined by a time difference between the both signals, and therefore, it is possible to find a distance and a relative speed with the object, and so on.[0004]The FMCW signal for radar use is required to have a characteristic in which a frequency changes approximately linearly relative to the time. Conven...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): G01S13/34G01S7/40
CPCG01S7/4008G01S13/345
Inventor KOBAYASHI, YUKASAKURAI, HIROKI
Owner KK TOSHIBA